“He walked like a man, he climbed like a monkey” – a new species of hominid was discovered

About 2 million years ago, the Homo sapiens species became bipedal, but before that, many other things had happened. Some of the stages of evolution are still shrouded in mystery, and the analysis of the female remains australopithecus known as Issa, shed new light on the darkness of history.

“Issa walked a bit like a human, but could climb like a monkey,” said Lee Berger, a paleoanthropologist at the University of Witwatersrand in South Africa.

In order to achieve an upright posture, the primate skeleton had to be reoriented significantly – from the feet to the knee joints to the spine. It must be remembered that the lower part of the human spine is curved inward, unlike monkeys and other apes. This pronounced curve (lordosis) helps us bear the weight of our massive upper body.

In 2008, 2 million years old fossils of an adult female were found in Malapa, South Africa Australopithecus sediba. The missing fragments made it unclear whether her spine was straight or like that of modern humans.

“Associated series of lumbar vertebrae are extremely rare in the hominin fossil record – in fact, only three comparable lower parts of the spine are known from all over the early record of Africa,” said Scott Williams, an evolutionary morphologist at New York University.

The structure of Issa’s finger bones suggests that she was fine adapted to life in trees (like modern orangutans), as well as a very flexible foot joint, suitable for vertical climbing. Dental analysis suggests Issa’s diet was likely rich in fruit and leaves, as was that of the savannah chimpanzees, again suggesting an arboreal lifestyle. However, the angle at which her femur meets the knee joint suggests that she was able to stand upright.

In 2015, two fossils of the lower vertebrae of the spine were found that fit perfectly with Issa’s remains. Computed microtomography studies confirmed that the species did indeed have a curved lower back. This is the ultimate proof that this creature was bipedal (at least partially).

The researchers argue that Issa “could and did climb using her upper limbs as well as many apes, but also shows that she could walk on two legs exceptionally well.”

Unfortunately, at the moment it is not known what this means in terms of the position of Australopithecus sediba in ours family tree. It is not known whether this species was a dead end of evolution or our immediate ancestor.

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